Big wind power: seven questions for turbulence research

Meneveau, Charles

doi:10.1080/14685248.2019.1584664

Cited by 77 publications

(51 citation statements)

References 86 publications

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“…Finally, the regional intensity of the resource may be affected by changes in the climate (52), raising issues of siting and profitability for future wind power plant development. For more detailed research questions specific to relevant subdisciplines, including meteorology research and fluid turbulence, see (53) and (54), respectively.…”

Section: First Grand Challenge: Improved Understanding Of Atmosphericmentioning

confidence: 99%

Grand challenges in the science of wind energy

Veers

Dykes

Lantz

et al. 2019

Science

Self Cite

672

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Harvested by advanced technical systems honed over decades of research and development, wind energy has become a mainstream energy resource. However, continued innovation is needed to realize the potential of wind to serve the global demand for clean energy. Here, we outline three interdependent, cross-disciplinary grand challenges underpinning this research endeavor. The first is the need for a deeper understanding of the physics of atmospheric flow in the critical zone of plant operation. The second involves science and engineering of the largest dynamic, rotating machines in the world. The third encompasses optimization and control of fleets of wind plants working synergistically within the electricity grid. Addressing these challenges could enable wind power to provide as much as half of our global electricity needs and perhaps beyond.

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Section: First Grand Challenge: Improved Understanding Of Atmosphericmentioning

confidence: 99%

Grand challenges in the science of wind energy

Veers

Dykes

Lantz

et al. 2019

Science

Self Cite

672

342

View full text Add to dashboard Cite

show abstract

“…Therefore, whether the wake rotation has more important effects for other values of rotor spacing remains an open question and can be addressed in future works. Moreover, it is important to note that in very large wind farms, vertical turbulent kinetic energy flux is the main mechanism of energy transport from the flow above into the wind farm array 31,32,52,53 . For large wind farms consisting of MR turbines, therefore, cases such as R4 and R6 are might be of interest as they can generate an additional vertical flux of kinetic energy driven by mean swirl motions.…”

Section: R2 R3mentioning

confidence: 99%

Multirotor wind turbine wakes

Bastankhah

Abkar

2019

Physics of Fluids

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To fulfill the increasing need for large power generation by wind turbines, the concept of multi-rotor wind turbines has recently received attention as a promising alternative to conventional massive single-rotor wind turbines. To shed light on the viability of this concept, large-eddy simulation is employed in this study to compare wake flow properties of a multi-rotor wind turbine with those of a single-rotor turbine. The wake of a multi-rotor turbine is found to recover faster at short downwind distances, where the whole wake is characterized as an array of localized high velocity-deficit regions associated with each rotor. However, as the wake moves downstream, rotor wakes start interacting with each other until they eventually form a single wake. This transition from a wake array to a single wake adversely affects the initial fast recovery of multirotor turbine wakes. A budget analysis of mean kinetic energy is performed to analyze the energy transport into the wake before and after this transition. In addition, the effect of different geometrical configurations on wake characteristics of a multi-rotor turbine was examined. We found that the recovery rate of multi-rotor turbine wakes is enhanced by the increase of rotor spacing, whereas the number and rotation direction of rotors do not play a significant role in the wake recovery. A simple analytical relationship is also developed to predict the streamwise distance at which the transition from a wake array to a single wake occurs for multi-rotor wind turbines.

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“…This degradation in performance occurs because the wakes of other turbines reduce the energy available in the wind. Despite the economic importance of these losses, a general, theoretical performance limit for wind farms is not known, as recently noted by Meneveau [2]. Wind turbine performance is often measured in terms of a power coefficient C P , which is the ratio of power generated by the turbine to the power available in the wind, if the turbine were not there.…”

Section: Introductionmentioning

confidence: 99%

Wind Turbine Performance in Very Large Wind Farms: Betz Analysis Revisited

West

Lele

2020

Energies

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The theoretical limit for wind turbine performance, the so-called Betz limit, arises from an inviscid, irrotational analysis of the streamtube around an actuator disk. In a wind farm in the atmospheric boundary layer, the physics are considerably more complex, encompassing shear, turbulent transport, and wakes from other turbines. In this study, the mean flow streamtube around a wind turbine in a wind farm is investigated with large eddy simulations of a periodic array of actuator disks in half-channel flow at a range of turbine thrust coefficients. Momentum and mean kinetic energy budgets are presented, connecting the energy budget for an individual turbine to the wind farm performance as a whole. It is noted that boundary layer turbulence plays a key role in wake recovery and energy conversion when considering the entire wind farm. The wind farm power coefficient is maximized when the work done by Reynolds stress on the periphery of the streamtube is maximized, although some mean kinetic energy is also dissipated into turbulence. This results in an optimal value of thrust coefficient lower than the traditional Betz result. The simulation results are used to evaluate Nishino’s model of infinite wind farms, and design trade-offs described by it are presented.

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Big wind power: seven questions for turbulence research

Cited by 77 publications

References 86 publications

Grand challenges in the science of wind energy

Grand challenges in the science of wind energy

Multirotor wind turbine wakes

Wind Turbine Performance in Very Large Wind Farms: Betz Analysis Revisited

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